The long-range goals of this proposal are to better understand the molecular neurobiological events that underlie the development of excessive alcohol drinking, and contribute to the long-range consequences of excessive alcohol drinking. The overall hypothesis to be tested is that changes in the expression of genes involved in neurotransmission, neuroplasticity, and intracellular signaling pathways within discrete regions of the extended amydala (E-AMYG) contribute to the development of excessive alcohol drinking. Excessive drinking is defined as sustainable blood alcohol concentrations (BACs) in the range of 100-150 mg% that are repeatedly attained over a chronic period. The overall hypothesis will be tested using selectively bred alcohol-preferring (P) and high-alcohol-drinking (HAD) rats. Micro-punch techniques will be used to obtain samples containing the nucleus accumbens shell (ACB-sh) and central nucleus of the amygdala (CeA). Changes in gene expression will be determined using Affymetrix microarrays. RT-PCR and in situ hybridization will be used to verify key findings from the microarray experiments. The excessive alcoholdrinking paradigm to be used will be the 'drinking in the dark multiple scheduled access'(DID-MSA) procedure. Time-course changes in gene expression will be determined following a drinking episode, and during the development of excessive alcohol drinking. The specific aims will be designed to determine changes in gene expression within the ACB-sh and CeA of P and HAD rats prior to, during initiation of, and following development of excessive alcohol drinking. The effects of chronic alcohol exposure and the development of excessive alcohol drinking are influenced by multiple genetic and environmental factors. This project will provide important molecular neurobiological information in discrete regions of the E-AMYG of genetically vulnerable subjects that could more comprehensively describe the complex inter- and intracellular events leading to the development, maintenance, and consequences of excessive alcohol drinking. Such information would be critically important for developing pharmacotherapeutic strategies to treat alcoholism and alcohol abuse.